S1) Investigative Techniques Flashcards

1
Q

Identify 3 requirements for light microscopy

A
  • Formalin
  • Paraffin
  • Haematoxylin and Eosin
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2
Q

What role does formalin have in light microscopy?

A

Formalin preserves tissue to prevent it from rotting

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3
Q

What role does paraffin have in light microscopy?

A

Paraffin embeds the tissue in a substance that allows it to be sliced very thinly

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4
Q

What role does H&E have in light microscopy?

A

Haematoxylin and Eosin stains the tissue so that we can see cell components

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5
Q

Describe the process of producing a frozen section

A
  • The surgical specimen is placed on a metal disc then frozen rapidly to -20°C to -30°C
  • The specimen is cut open with a cryostat
  • The tissue is then stained with H&E
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6
Q

Identify an advantage and a disadvantage of frozen sections

A
  • Advantage: prepared more rapidly than traditional histology (10 minutes vs 16 hours)
  • Disadvantage: technical quality of sections is much lower
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7
Q

Outline the process of fluorescent microscopy

A
  • Specimen has fluorescent molecules (fluorophores) attached
  • Fluorophores emit light when they are irradiated by a specific wavelength of light
  • Colours observed can be different components of a cell or the different cell types within a tissue
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8
Q

When is fluorescent microscopy most commonly used?

A

Used in the differentiation of different cancer cell types

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9
Q

Outline the process of confocal microscopy

A

Often combined with fluorescent imaging:

  • Fluorescent dye molecules are attached to specific parts of a sample
  • Only the labelled parts can be seen in the confocal microscope
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10
Q

Identify and describe 3 advantages of confocal microscopy

A
  • Produces a sharper image (blocks out of focus light)
  • Captures 3D images of specimens
  • Allows for imaging of live specimens (images taken at time intervals to create a time-lapse video)
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11
Q

Outline the process of autoradiography

A

A photographic emulsion is used to visualise molecules labelled with a radioactive marker:

  • Marker is injected into the live animal/cell culture
  • Histological section is coated with the emulsion
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12
Q

What is an ultrasound?

A

Ultrasound are sound waves with frequencies which are higher than those audible to humans (>20,000 Hz)

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13
Q

Describe the process of performing an ultrasound

A
  • Ultrasonic images are sonograms and are made by sending pulses of ultrasound into tissue using a probe
  • The sound echoes off the tissue
  • Different tissues reflecting varying degrees of sound
  • Echoes are recorded and displayed as an image
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14
Q

Describe the use and aim of the ultrasound

A
  • Use: view internal body structures
  • Aim: find a source of a disease or to exclude any pathology
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15
Q

Outline the process involved in Transmission Electron Microscopy

A
  • Uses an electron beam generated in a vacuum
  • The electron beam passes through the tissue
  • Portions that the beam has passed through appear bright
  • Portions that have absorbed or scatter electrons appear dark
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16
Q

Make a relative comparison of electron microscopy with light microscopy in terms of:

  • Resolution
  • Magnification
A
  • Resolution: 400 x that of light microscopy
  • Magnification: 250 x that of light microscopy
17
Q

Outline the process involved in Freeze Fracture Electron Microscopy

A
  • The tissue is frozen to -160°C and fractured by hitting with a knife edge.
  • The fracture line passes through the plasma membrane exposing its interior which can then be imaged
18
Q

Outline the process involved with Scanning Electron Microscopy

A

The electrons are reflected from the surface and received by a cathode ray tube (like a TV)

19
Q

What is MRI?

A

MRI is a useful non-invasive and non-destructive diagnostic tool for imaging soft tissues such as the brain, heart and muscles, and for discovering tumors in many organs